Method of fabricating a composite material connecting rod

Abstract

The invention relates to a method of fabricating a composite material connecting rod, the method comprising the step of cutting out a pattern presenting two opposite edges from a composite fiber fabric made up of a plurality of superposed primary plies that are bonded together in such a manner that the primary plies can slide relative to one another, rolling the pattern into a tube in such a manner that the primary plies slide relative to one another to give a chamfer shape to the two edges, and joining together the chamfer-shaped edges so that they overlap.

1. A method of fabricating a composite material connecting rod, the method comprising the step of cutting out a pattern presenting two opposite edges from a composite fiber fabric made up of a plurality of superposed primary plies that are bonded together in such a manner that the primary plies can slide relative to one another and wherein the pattern is cut out in such a manner that it presents at least two extensions that come to face each other when the pattern is formed into a tube, rolling the pattern into a tube in such a manner that the primary plies slide relative to one another to give a chamfer shape to the two edges, joining together the chamfer-shaped edges so that they overlap, forming a connecting means adjacent at least one of a first end of the tube and a second end of the tube, the step of forming a connecting means including separating the primary plies in the extensions from one another and inserting intermediate plies of composite fiber in between the primary plies, and diffusing resin into the fabric of the tube by resin transfer molding. 
     
     
       2. A method according to  claim 1 , in which the pattern is cut from a fabric comprising a base weave which is constituted:
 firstly by at least twenty-eight weft fibers organized in at least eight columns each extending in the thickness direction of the fabric, and disposed in a staggered configuration with alternation between columns having at least three superposed weft fibers spaced apart at a predetermined pitch, and columns having at least four superposed weft fibers spaced apart by the same pitch, the weft fibers extending to define at least seven primary plies; and 
 secondly, by at least twelve warp fibers disposed in at least four parallel planes that are offset in the weft fiber direction, each plane containing three superposed parallel warp fibers arranged in each of these planes as follows:
 a first warp fiber connects the topmost warp fiber of a four-weft fiber column to an upper intermediate weft fiber of a four-weft fiber column that is spaced apart from the preceding column by at least two pitch steps, the first warp fiber returning over a top end weft fiber of a four-weft fiber column that is spaced apart from the first column by at least four pitch steps; 
 a second warp fiber connecting a top intermediate weft fiber of a four-weft fiber column to a lower intermediate weft fiber of a four-weft fiber column that is spaced apart from the preceding column by at least two pitch steps, the second warp fiber returning over an upper intermediate weft fiber of a four-weft fiber column that is spaced apart from the first column by at least four pitch steps; and 
 a third warp fiber connecting a lower intermediate weft fiber of a four-weft fiber column to the bottommost weft fiber of a four-weft fiber column spaced apart from the preceding column by at least two pitch steps, the third warp fiber returning over a lower intermediate weft fiber of a four-weft fiber column that is spaced apart from the first column by at least four pitch steps; 
 
 the positions of the parallel warp fibers being offset longitudinally by one pitch step from one plane to another. 
 
     
     
       3. A method according to  claim 2 , in which the pattern has an axis of symmetry and is cut out from said fabric in such a manner that the primary plies have weft fibers that extend along the axis of symmetry. 
     
     
       4. A method according to  claim 1 , in which the intermediate plies have fibers that are oriented obliquely relative to the weft fibers forming the primary plies in the extension. 
     
     
       5. A method according to  claim 1 , in which transverse fibers are inserted through the primary plies and the intermediate plies. 
     
     
       6. A method according to  claim 1 , in which, after resin has been injected and polymerized, the extensions are pierced to form lugs of coupling forks. 
     
     
       7. A method according to  claim 6 , in which the holes pierced are fitted with pairs of rings. 
     
     
       8. A method of fabricating a composite material connecting rod, the method comprising the step of cutting out a pattern presenting two opposite edges from a composite fiber fabric made up of a plurality of superposed primary plies that are bonded together in such a manner that the primary plies can slide relative to one another, rolling the pattern into a tube in such a manner that the primary plies slide relative to one another to give a chamfer shape to the two edges, joining together the chamfer-shaped edges so that they overlap, forming a connecting means adjacent at least one of a first end of the tube and a second end of the tube, and diffusing resin into the fabric of the tube by resin transfer molding. 
     
     
       9. A method according to  claim 8 , in which the pattern is cut from a fabric comprising a base weave which is constituted:
 firstly by at least twenty-eight weft fibers organized in at least eight columns each extending in the thickness direction of the fabric, and disposed in a staggered configuration with alternation between columns having at least three superposed weft fibers spaced apart at a predetermined pitch, and columns having at least four superposed weft fibers spaced apart by the same pitch, the weft fibers extending to define at least seven primary plies; and 
 secondly, by at least twelve warp fibers disposed in at least four parallel planes that are offset in the weft fiber direction, each plane containing three superposed parallel warp fibers arranged in each of these planes as follows:
 a first warp fiber connects the topmost warp fiber of a four-weft fiber column to an upper intermediate weft fiber of a four-weft fiber column that is spaced apart from the preceding column by at least two pitch steps, the first warp fiber returning over a top end weft fiber of a four-weft fiber column that is spaced apart from the first column by at least four pitch steps; 
 a second warp fiber connecting a top intermediate weft fiber of a four-weft fiber column to a lower intermediate weft fiber of a four-weft fiber column that is spaced apart from the preceding column by at least two pitch steps, the second warp fiber returning over an upper intermediate weft fiber of a four-weft fiber column that is spaced apart from the first column by at least four pitch steps; and 
 a third warp fiber connecting a lower intermediate weft fiber of a four-weft fiber column to the bottommost weft fiber of a four-weft fiber column spaced apart from the preceding column by at least two pitch steps, the third warp fiber returning over a lower intermediate weft fiber of a four-weft fiber column that is spaced apart from the first column by at least four pitch steps; 
 
 the positions of the parallel warp fibers being offset longitudinally by one pitch step from one plane to another. 
 
     
     
       10. A method according to  claim 9 , in which the pattern has an axis of symmetry and is cut out from said fabric in such a manner that the primary plies have weft fibers that extend along the axis of symmetry.